My pattern calls for bernat denimstyle which has a guage of 18 st. per 4 inches (8 needles). I want to use a solid colored yarn instead of a variagated one, and I'd rather use a yarn that's either a wool or an acrylic/wool blend. Any ideas for a substitution?

Hi! Lion Brand Wool-Ease is the same weight (worsted). If you go to some of the large yarn company sites (Lion, Bernat, Patons) you will find ways of substituting yarns by weight and gauge. Have fun! These sites have tons of free patterns.